Process of vulcanizing rubber and accelerator therefor



Patented a. 28,. 1930- i No Drawing.

A v UNITED STATES ,DONAVIQDVH. rownns, or PENNSzGROVE, NEW JERSEY, ASSIGNOR TOE. I. DU, FONT DE AT OFF-110E NEMIOU'RS & CQIVIJE'ANY, 0F WILMINGTON, DELAWARE, A CORPORATION OF DELA- ,WARE I v V PROCESS VULG ANIZING RUBBER AND ACCELER-A'IfOR THEREFOR This invention relates to the vulcanization, of rubber or slmllarmaterlals such as balata,

guttapercha. and rubber substitutes. It is more particularly directed "to vulcanization hydesi i One object ;of thisinvention is 'to provide a process for the vulcanization of rubber involving theuse of'a material which 7 shall require a shorter, time of cure, and will .not cause,over-vulcanization as do other actime. possess the abovementioned desirable proper.-

pressure.

celerators well known in the art, Anotherobject is to provide a processaccording to strength throughoutya wide range'of cures. J Ibis wellknownthataldehyde-amines in general possess accelerating valueand may be used over a limitedrangeof conditions, usually vulcanizmg at ,forty poundss'team using as accelerators certain "new classes of compounds of the general type mentioned above, it is possibletoiefiect vulcanization at materially lower temperatures than have heretofore been commonly used. With these new accelerators, jl have fo'undrit possible to obtain vulcanization over a long range of time at a temperature of'120' (1.; and they possess this -further advantage that below 100"" C. they showg-but slight vulcanizing action, with the result thatfthey are free from the scorching properties which characterize, anddetract from the value of, a great many of theaccelerators usedat; the present This new class of accelerators which ties are compounds-resulting from the action of an aldehyde on the condensation product of analiphatic aldehyde andan aliphaticamine." I

For practical reasons I'prefer to use as accelerators those compounds whichmaybe is produced by 'causingzthe condensation product of an aliphatic :amine. and an aliphatic aldehyde to react with formaldehyde ;Goo.d results have also beenobtained, however,

I have new discovered that by typical: I i

Ethylidene-ethyl-amine treated with form aldehyde. 9 v l a 7 Ethylidene-methylamine treated V with,

aldehyde;

Application filed January 26, 1926; Serial No. 83,952.

be described as thecondensation product of i one molecular proportion of an aliphatic aldehyde, preferably containing more than one carbon atom, with one molecular proportion of an aliphatic amine. The resulting alkylidene-alkyl-amine has most probably the following general graphical formula: R=NR where R stands for an alkylidene radical, alkyl group. I V. a M

The product obtained by causingan aliphati'c' aldehyde to act on the above described .alkylidene-alkyl-amine appearstohave a i rather complexmolecular structure the ex- ;act nature of whichhas not as yet been as- .certalned. Y

As examples of these new accelerators, the following may be cited, 1t beingunderstood, of course, that these examples are merely formaldehydeq;

Ethylidene-butylamine treated with form aldehyde.

Propylideneethanol amine treated with formaldehyde;

' Propylidene-propylsamine treated .With

Methylene-amyleamine treated with form- Butylidene-butylamine treated with form; aldehyde; I

Butylidene methylainine treated sme rsand R represents, an 7 formaldehyde. I

Heptylidene-methylainine"" treated with formaldehyde. i i f H i Heptylidene-"ethyl' amine treated with ar amehyde;

T Heptylidene=iso' propyl-aminetreated with illustrated as follows:

pounds of 3072} ethyl-amine is slowly Methylene-isopro1')yl-aniine treated with butyraldehyde.

Methylene-ethyl-amine treated with heptaldehyde.

The amount of aldehyde which is usually I, treated with alkylidene-alkyl-amine isfrom one to two moles of aldehyde with two moles of the alkylidene-alkyl-ainino.

A preferred method of preparation may be Ezcamplc I One hundred pounds of acetaldchyde is cooled to (I. and three hundred and forty added, keeping the solution cooled to C. lVhen the addition is complete the alkylidene-alkylamine solution is warmed to C. Two hundred and fifty pounds of 37 formaldehyde is rapidly run in. A vigorous heat of reaction is noted and care used to avoid 1 overheating. The resulting product, obtained by this action of formaldehyde on ow oil.

In applying these newaccelerators to the vulcanization of rubber, I preferably employ from 0.25 to 0.75 parts of the accelerator for parts of rubber mixed with 3 parts of zinc elihylidene-ethyl-amine, separates asa light oxide and 3.5 partsof sulphur. These sLib-' stances are mixed together by milling on the rolls in the usual manner, and vuloanizing in a press under thirty pounds steam pressure for thirty minutes.

Using as the specific accelerator the 'ethylidene-ethyl-amine-formaldehyde reaction product produced as described in Example I above, in a rubber mix such as that just described, and curing for thirty minutes at thirty pounds steam pressure,'there was obtained a stock having a tensile strength "close to three thousand pounds (2970) when one per cent. of too accelerator. wasused.

Example [I One hundred and fifty pounds of forty per cent. monomethylamine"is slowly added to two hundred and twenty-five pounds of heptaldehyde. The alkylidene-alkyl-amine was treated with eighty-five pounds of; thirtyseven'per cent; formaldehyde, The resulting product is a colorlesswatcr-insoluble oil which is readily separated.

This product was tested in a stock containinglOO parts of rubber, 3 parts of zincoxide,

3.5 parts of sulfur and .37 5parts ofthis ac celerator. When cured for thirty minutes at twenty-five pounds steam pressure, a. product having a tensile strength of over 4,400pounds (4,456) per square inch is obtained,

Although the accelerators described herein are in general the reaction products of aldehydes and alkylidene-alkyl-amines, I

i have found of'special-val'ue those accelerators as obtainable by the action of an aliphatic aldehyde having from one to seven carbon atoms on an alkylidene-alkyl-amine in which the alkylidene and the alkyl radicals each has from one to seven carbon atoms. For the aliphatic aldehyde, formaldehyde is =considered preferable; and by formaldehyde I include paraformaldehyde and various other forms of polymerized formaldehyde which are equiva cut to, and'which'may be used in place of, formaldehyde itself.

My new accelerators are in general differentiated from the eth lidene-aniline-aldehyde accelerators descri ed inUnited States Patent No. 1,467,984 to North bythe fact, among others, that they can effect satisfactory vulcanization-ata steam pressure of thirty pounds or less, compared with a steam pressureof torty pounds 'for the ethylideneof an aliphatic aldehyde nnd an a 'plratic -'mole of an aliphatic amine.

3. A rubber-vulcanization accelerator comprising the product resultingfimn the action "ofan aliphatic aldehyde on the condensation productofan aliphatic aldehyde'and an aliphatic amine. I

Arubber-vulcanizution accelerator comprising the reaction product of en aldehyde and an alky-lidene-alkyl-amine.

5. A rubber vulcanizatimi accelerator comprising the reaction product of an aliphatic aldehyde and an alkylidene alkylq ini ne, said product when used as an accelerator making 7 possible theproduetion of a satisfactory vulcanized rubber by vulcanizing a rubher mix for less than an hour at not more than thirty pounds steam pressure;

'6; Arubber-vulcanization accelerator comprising the reaction roduct of from one'to two moles of an alipl iatic aldehyde andtwo moles of an alkylidene-al'kyl-amine.

'7. A rubber-vulcanization accelerator comprising the reaction product of from one to two moles of a straight'chain aldehyde and two moles of'an alkylidene-alkyl-aminc.

8. 'A rubber-vulcanization accelerator comprising the reaction rod'uct of an aliphatic aldehyde'and an alky 'dene-alkyl-amine, said aldehyde, and said alkylidene and said alkyl radicals, each having from one to seven carbon'atoms. I

'9. As a rubber-vulclmization accelerator,

. tile product obtainahlelby the action offrom one to two moles of "formaldehyde moles of an alkylidene alkyl amlne.

' carbon atoms,

r the reaction product of" from one to two moles of formaldehyde and two moles of an alkylidene-alltyl-amine, and vulcanizing the rubber rubber mix.

moles of an heptylidene-alkyl-aniine, said alkyl radical'having from one to seven carbon atoms.

14L The process of making a vulcanization accelerator which comprises condensing an aliphatic aldehyde with an aliphatic primary amine, and treating the resulting condensation product with an-aliphatic aldehyde.

15. The proceis s of making a vulcanizationaccelerator which comprises condensing two moles of an .aliphaticaldehyde having from one to sevenca' rbon atoms with about two moles of an aliphaticamine, and causing the resulting condensation product to react with from one to two moles of formaldehyde while cooling to prevent overheating.

16. The process oftreating rubber which comprises combining rubber with a vulcanizing agent and with an accelerator comprising the reaction product of an aldehyde and an alkylidene-alkyl-amine, and vulcanizing the 1'7. The process of treating rubber which comprises combining rubber Wltllfl. vulcanizing agent and with an accelerator corhprising the reaction product of an aliphatic aldehyde and'an alltylidene-alkyl-amine in which the alkylidene group has from oneto seven and vulcanizing the rubber mix.

18. The process of treating rubberwhich comprises combining rubber with a vulcanizing agent and with an accelerator comprisi ing the reaction product of formaldehyde and an alkylidcne-aikyl-amine,and vulcanizing the rubber mix; 2 7

- 19. The process of treating rubber which comprises combining'rubber with a Vulcanizing agent andwith anaccelerator comprising the reaction productof formaldehyde and an alkylidene alkyl-amine' in which the alkyl and allt lidene radicals each have from one i to seven carbon atoms, and vulcanizing the rubber mix. I a 20. The process of treating rubber which comprises combining rubber with a vulcanizing agent and with an accelerator comprising mix.

21. A process as. defined in claim 20 in c which the alkyl and alkylidene radicals of the alkylidenealkyl-amine each have from one to seven carbon atoms;

22. Arubber product obtainable by com- I bining rubberwith sulphur and with the reaction product of an aldehyde and an alkylidene-alkyl-amine, and vulcanizing the mixture.

23.: A rubber productcomprising rubber mixed with sulphur and with the reaction product of an aliphatic aldehyde and an alkylidene-alliyl-amine, and vulcanized. I

24. A rubber product comprising rubber mixed with sulphur, zinc oxide, and the reaction product of from one to two moles of formaldehyde and two moles .of an alkylidene-alkyl-amine, and vulcanized; v

.25. 'A rubber product as defined in claim 2 in which the alkyl and alkylidene radicals of the.alkylidene-alkyl-amine each have from one to seven carbon atoms. I

26. A rubber-vulcanization accelerator comprising the product resulting from the interaction of 1 mole of aliphatic amine and more than l mole of an aliphatic aldehyde.

27. A rubber-Vulcanization accelerator comprising the product resulting from the interaction of from 3 to at moles of aliphatic aldehyde with 2 moles of aliphatic amine.

28. A rubber-vulcanization accelerator comprising the product resulting from the interaction of formaldehyde, an aliphatic aldehyde containing a plurality of carbon 7 atoms and a primary aliphatic amine.

29. A rubber-vulcanization accelerator comprising the product resulting from the interaction of 1 to 2 moles of formaldehyde,

1 mole of aliphatic aldehydev containing plurality of carbon atoms and 1 mole of a primary aliphatic amine containing from 1' to 7 carbon atoms. V r

30. A rubber-vulcanization accelerator comprisingthe product resulting from the interaction of formaldehyde, heptaldehyde and.mono-methyl-amine.

31. A rubber product obtainable by combining rubber withavulcanizing agent and with the reaction product of an aliphatic aldehyde and a primary aliphatic amine, and 11-:

thereafter Vulcamzmg.

32. A rubber product obtainablebycoinbiningrubber with a vulcanizing agent and with the reaction product of an aliphatic aldehyde'containing from 1 to 7 carbon atoms and a primary-aliphatic aminencontaining' from Ito T vulcanizing. I

33. A rubber product obtainable by com- ,carbon atoms, and thereafter bining rubber with a vulcanizing agent and, with the reaction product of 1 mole of an. aliphatic amine and more than 1 mole of an aliphatic aldehyde, and thereafter vulcaniz-: v

ing.

A rubber product obtainable by com-.

billing rubber with a vulcanizing agent and with the reaction product of formaldehyde,

an aliphatic aldehyde containing a plurality of carbon atoms and a primary aliphatic 5 amine, and thereafter vulcanizing.

35. A rubber product obtainableby combining rubber with a vulcanizing agent and. with the reaction product of 1 to 2 moles of formaldehyde, 1 mole of aliphatic aldehyde 10 containing a plurality of carbon atoms and 1 mole of a primary aliphatic amine cont-aim ing from 1 to 7 carbon atoms, and thereafter vulcanizing.

36. A rubber product obtainable by combining rubber wltha cvulcanizing agentand with the reaction product of heptaldehydc, mono-methyl-amine and formaldehyde.

In testimony whereof I aflix my signature.

1 DONALD H. POVERS. 

